Trazodone’s sedative effects typically last 5 to 9 hours, which aligns with a full night of sleep for most people. The drug reaches peak concentration in about 1 hour on an empty stomach, and its half-life (the time it takes for half the drug to leave your system) ranges from 5 to 9 hours depending on individual metabolism. That means the sleepiness you feel will be strongest in the first few hours and gradually taper off through the night.
How Quickly It Kicks In
On an empty stomach, trazodone reaches its highest blood levels in roughly 1 hour. If you take it with food, that peak shifts to about 2 hours. Food also lowers the peak concentration while increasing the total amount your body absorbs, which means the sedation hits less sharply but may linger a bit longer. For sleep purposes, taking trazodone on an empty stomach produces a faster, more defined onset of drowsiness.
Most people feel noticeably sleepy within 30 to 60 minutes of taking it, which is why it’s typically taken right at bedtime rather than earlier in the evening.
How Long the Sleep Effects Last
Trazodone’s blood levels drop in two phases. In the first phase, levels fall relatively quickly with a half-life of about 3 to 6 hours. In the second, slower phase, the remaining drug clears with a half-life of 5 to 9 hours. Practically, this means the strongest sedation occurs during the first 3 to 4 hours, then gradually fades. By the 7- to 8-hour mark, most of the sleep-promoting effect has worn off.
Whether you still feel groggy in the morning depends on where you fall in that half-life range. People who metabolize the drug more slowly, or who take higher doses, are more likely to notice residual drowsiness the next day. A 50 mg dose and a 100 mg dose share the same half-life, so a higher dose doesn’t make the drug last dramatically longer. It does, however, produce a stronger peak effect, which can mean more morning grogginess simply because there’s more drug left in your system when the alarm goes off.
How Long It Takes to Fully Leave Your Body
A drug is generally considered cleared from your system after about 5 half-lives. With trazodone’s terminal half-life of 5 to 9 hours, that puts full clearance somewhere between 25 and 45 hours after your last dose. Less than 1% of the drug leaves your body unchanged; the liver breaks down nearly all of it before excretion.
Certain medications can slow this process significantly. Drugs that inhibit a specific liver enzyme responsible for breaking down trazodone can more than double its half-life. In one study, a common antiviral increased trazodone’s half-life by 2.2 times and cut the body’s clearance rate by 52%. Antifungal medications and some other prescriptions can have a similar effect. If you take any of these alongside trazodone, the drug stays active in your system considerably longer than the standard window.
Immediate-Release vs. Extended-Release
The immediate-release tablet is the formulation most commonly used for sleep. It produces a sharp peak in blood levels followed by a steady decline, which is exactly what you want: quick sedation that fades by morning.
The extended-release version was designed for depression rather than insomnia. It smooths out the peaks and troughs, delivering a more consistent level of the drug throughout the day. Interestingly, the actual half-life is the same for both formulations. The difference is only in how quickly the pill releases the drug into your system, not how fast your body eliminates it. A single 300 mg extended-release tablet produces steady blood levels equivalent to taking 100 mg of the immediate-release version three times a day, but with a lower peak concentration. This reduces daytime sedation, which was a major barrier to using the immediate-release form for depression.
Sleep Effects vs. Antidepressant Effects
The sedative effect of trazodone and its antidepressant effect operate on very different timelines. Sedation begins within the first hour and works from the very first dose. The antidepressant effect is far slower. You may notice some mood changes within 1 to 2 weeks, but the full antidepressant benefit typically takes 4 to 6 weeks to develop.
This distinction matters because many people are prescribed trazodone specifically for sleep at doses lower than those used for depression (commonly 25 to 100 mg for sleep versus 150 to 400 mg for depression). At these lower doses, the sedation is the primary effect, and the question of “how long does it last” is really about whether you’ll sleep through the night and wake up feeling clear. For most people at typical sleep doses, the answer is yes on both counts, provided they give themselves a full 7 to 8 hours in bed.
Factors That Change How Long It Lasts
- Food: Eating before or with trazodone delays peak sedation by about an hour and softens the intensity, potentially stretching mild drowsiness further into the morning.
- Age: Older adults tend to metabolize drugs more slowly, which can extend trazodone’s effective duration and increase next-day grogginess.
- Other medications: Drugs that inhibit the liver enzyme CYP3A4 can roughly double trazodone’s half-life, making it last well into the following day.
- Dose: Higher doses don’t change the half-life, but they mean more drug is still circulating at any given point, making residual effects more noticeable.
- Liver function: Because the liver handles nearly all of trazodone’s breakdown, reduced liver function slows clearance and extends the drug’s effects.